U.S. Pat. No. 4,116,858 and U.S. Pat. No. 4,159,311, disclose that an ion exchange resin may be saturated with aqueous AlCl.sub.3 solution and that reaction with NH.sub.4 OH converts the AlCl.sub.3 in situ to Al(OH).sub.3. This so-formed amorphous Al(OH).sub.3 is then reacted with LiX, where X is halide, at elevated temperature to form crystalline LiX.2Al(OH).sub.3 which is useful in selectively recovering Li.sup.+ values from aqueous solutions, e.g., Li-containing brines.
U.S. Pat. No. 4,116,856 and U.S. Pat. No. 4,221,767 disclose that improvements in the above discussed formation of crystalline LiX.2Al(OH).sub.3 are found by reacting amorphous Al(OH).sub.3, or crystalline hydrous alumina (e.g., norstrandite, bayerite, gibbsite or mixtures of these) with LiOH to form LiOH.2Al(OH).sub.3 nH.sub.2 O which is then reacted with LiX to form the crystalline LiX.2Al(OH).sub.3, where X is halide.
Various forms of alumina, Al.sub.2 O.sub.3, are known, some of which occur as natural minerals, some of which are hydrated, and some of which are crystalline. The Handbook of Chemistry shows the following:
______________________________________ Crystalline Name Form M.P. .degree.C. ______________________________________ aluminum oxide, Al.sub.2 O.sub.3 hex. col. 2050 .alpha.-Al.sub.2 O.sub.3, corundum trig; col. cr, n 2015 .gamma.-Al.sub.2 O.sub.3, .gamma.-alumina wh. micro. cr., n tr. to alpha Al.sub.2 O.sub.3.3H.sub.2 O, gibbsite, monocl., wh. cr. tr. to Al.sub.2 O.sub.3.H.sub.2 O (hydrargillite) (Boehmite) Al.sub.2 O.sub.3.3H.sub.2 O, bayerite wh. micro. cr tr. to Al.sub.2 O.sub.3.H.sub.2 O (Boehmite) aluminum oxide, amor. wh. pwd. xH.sub.2 O, tr. to Al.sub.2 O.sub.3.xH.sub.2 O .gamma.-Al.sub.2 O.sub.3 ______________________________________
Norstrandite is a crystalline hydrous alumina, as are gibbsite and bayerite.
The present disclosure is believed to be most closely related to the above-identified patents and the patents are incorporated by reference in their entirety here. The teachings in U.S. Pat. No. 4,116,856 are particularly relevant where it discloses that crystalline hydrous alumina (e.g., norstrandite and/or bayerite) dispersed in ion exchange resin is not converted back to its original LiX.2Al(OH).sub.3.nH.sub.2 O form by treatment with LiX unless the hydrous alumina is first, or simultaneously, reacted with LiOH. I have found, however, that crystalline hydrous aluminas can be reacted directly with lithium salts to form crystalline lithium salt aluminates if the correct ranges of temperature and concentration are employed. I have also found that 2-layer lithium aluminate can be regenerated, without conversion to gibbsite, by employing an aqueous wash containing at least about 800 ppm. Li.sup.+. I have further found that crystalline 2-layer LiOH.2Al(OH).sub.3.nH.sub.2 O can be prepared by treating crystalline 2-layer LiX.2Al(OH).sub.3.nH.sub.2 O with LiOH.